AngelAirways
Posts: 481
Joined: Wed Nov 10, 1999 3:55 am

777 Fuel Consumption

Tue Apr 26, 2005 4:11 am

Is there anybody here who knows what the fuel consumption looks like for a 777-200ER (any engine type). This can be specific fuel consumption, per mile/kilometre or per flying hour. Just looking for some rough figures.

Thanks  Smile
 
Boeing7E7
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RE: 777 Fuel Consumption

Tue Apr 26, 2005 4:14 am

It varies with configuration and route use, but about 2,100 and 2,200 Gallons per hour.
 
PolAir
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RE: 777 Fuel Consumption

Tue Apr 26, 2005 6:35 am

Hmm, I was thinking something in range of 15,000-20,000 lbs/hr depending on altitude, weight, wx etc...
 
AA737-823
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RE: 777 Fuel Consumption

Tue Apr 26, 2005 8:49 am

You have got to be kidding.
at 20000 lb per hour, the 777 would only fly for 4-5 hours.
And it's making 15+ hours flights.
 
ktachiya
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RE: 777 Fuel Consumption

Tue Apr 26, 2005 1:25 pm

Well, it has to be more economical than a 744, that's why you see many airlines flying T7's trans-pac rather than MD-11, 747-400/classics, etc.
Flown on: DC-10-30, B747-200B, B747-300, B747-300SR, B747-400, B747-400D, B767-300, B777-200, B777-200ER, B777-300
 
N1120A
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RE: 777 Fuel Consumption

Tue Apr 26, 2005 2:00 pm

Quoting Ktachiya (Reply 4):
Well, it has to be more economical than a 744, that's why you see many airlines flying T7's trans-pac rather than MD-11, 747-400/classics, etc.

It is not more economical than the 744. It burns less fuel, but still carries fewer passengers and has a higher seat-mile cost. Also, the 744 still dominates the pacific
Mangeons les French fries, mais surtout pratiquons avec fierte le French kiss
 
NAV20
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RE: 777 Fuel Consumption

Tue Apr 26, 2005 2:45 pm

Boeing's figures are:-

777-200ER - Fuel 45,520 US gallons (171,160 litres). Passengers (3 classes) 301. Range 7,730 nms. Therefore 5.85 gallons per mile, 150 gallons per passenger.

747-400ER - Fuel 63,705 gallons (241,140 litres). Passengers (3 classes) 416. Range 7,670 nms. Therefore 8.3 gallons per mile, 153 gallons per passenger.

http://www.boeing.com/commercial/flash.html

[Edited 2005-04-26 07:49:39]
"Once you have flown, you will walk the earth with your eyes turned skywards.." - Leonardo da Vinci
 
PADSpot
Posts: 1637
Joined: Sat Jan 15, 2005 11:31 pm

RE: 777 Fuel Consumption

Tue Apr 26, 2005 6:20 pm

Quoting NAV20 (Reply 6):
Boeing's figures are:-

777-200ER - Fuel 45,520 US gallons (171,160 litres). Passengers (3 classes) 301. Range 7,730 nms. Therefore 5.85 gallons per mile, 150 gallons per passenger.

747-400ER - Fuel 63,705 gallons (241,140 litres). Passengers (3 classes) 416. Range 7,670 nms. Therefore 8.3 gallons per mile, 153 gallons per passenger.

Ooouuuuhhhhh .... I guess that is a little too simplified calculation (No Weather/Route consideration, Marketing figures etc.) !!!! In German we have the nice and handy word "Milchmädchen-Rechnung" for something like that ... but there doesn't seem to be a good translation.

Edit: George Bush Senior called it "voodoo economics" in 1980 ...

[Edited 2005-04-26 11:34:16]
 
NAV20
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RE: 777 Fuel Consumption

Tue Apr 26, 2005 7:13 pm

Quoting PADSpot (Reply 7):
I guess that is a little too simplified calculation (No Weather/Route consideration, Marketing figures etc.) !!!!

Why take into account factors that would affect all aeroplanes equally, PADSpot? In any case, AngelAirways only asked for rough figures.

Anyway, sorry the figures aren't complicated enough for you.  Smile We have a saying here too (in English) - "KISS - Keep It Simple, Stupid."
"Once you have flown, you will walk the earth with your eyes turned skywards.." - Leonardo da Vinci
 
widebodyphotog
Posts: 885
Joined: Wed Jun 30, 1999 9:23 am

RE: 777 Fuel Consumption

Tue Apr 26, 2005 8:15 pm

Quoting NAV20 (Reply 6):
777-200ER - Fuel 45,520 US gallons (171,160 litres). Passengers (3 classes) 301. Range 7,730 nms. Therefore 5.85 gallons per mile, 150 gallons per passenger.

747-400ER - Fuel 63,705 gallons (241,140 litres). Passengers (3 classes) 416. Range 7,670 nms. Therefore 8.3 gallons per mile, 153 gallons per passenger.

This is vastly over simplified and fundamentally incorrect...

It's not that the the figures are too simplified it is that you are making some incorrect assumptions.

Neither aircraft uses it's entire fuel capacity to make the ranges you specify. At the very least the aircraft has to land with a specified reserves on a legal flight. The 747-400ER can not load maximum fuel and 416 passengers at the same time, as this would put the aircraft over it's 910,000lb MTOW.

Some figures

The fuel consumption for 777-300ER is nearly 17,000lb/h when taking off at an MTOW of 775,000lbs while the 747-400ER has a rate of fuel consumption of 24,100lbs taking off at an MTOW of 910,000lbs.

Fuel consumption for the 777-200ER varies with engine type but for a PW powered aircraft at 648,000lbs MTOW 14,400lb/h, a Trent 892 powered aircraft at 656,000lbs uses 14,600lb/h, and a GE90-94B powered 777-200ER burns 14,200lb/h at the higher MTOW.

All the fuel consumption rates are initial cruise fuel burn rates after taking off at certified MTOW.

I'll leave it up to the other folks to do the division on fuel per passenger or whatever, but using an aircrafts specified fuel capacity to determine mission fuel burn or rate of consumption is a shaky starting point at best.
If you know what's really going on then you'll know what to do
 
NAV20
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RE: 777 Fuel Consumption

Tue Apr 26, 2005 8:41 pm

Agree entirely that there are lots of variables, Widebodyphotog. But they would tend, as I said, to average out, since they are likely to affect all aeroplanes equally. Further, the question was:-

Quoting Angelairways (Thread starter):
Is there anybody here who knows what the fuel consumption looks like for a 777-200ER (any engine type). This can be specific fuel consumption, per mile/kilometre or per flying hour. Just looking for some rough figures.

I'm the only person who has offered any kind of answer so far. If you can produce a more sophisticated and accurate analysis, please put it on. Otherwise, I don't see the point of criticising my figures while offering none at all of your own?
"Once you have flown, you will walk the earth with your eyes turned skywards.." - Leonardo da Vinci
 
PADSpot
Posts: 1637
Joined: Sat Jan 15, 2005 11:31 pm

RE: 777 Fuel Consumption

Tue Apr 26, 2005 9:06 pm

Quoting NAV20 (Reply 8):
Quoting PADSpot (Reply 7):
I guess that is a little too simplified calculation (No Weather/Route consideration, Marketing figures etc.) !!!!

Why take into account factors that would affect all aeroplanes equally, PADSpot? In any case, AngelAirways only asked for rough figures.

Anyway, sorry the figures aren't complicated enough for you. Smile We have a saying here too (in English) - "KISS - Keep It Simple, Stupid."

LoL .. haha ... thanks for the lecture! It wasn't meant personally and I apparently read over that he asked for rough figures. It is just that being imprecise or even incorrect either leads to a good verbal threshing or to being ignored on this forum. Maybe that rubbed off on me ...

Jan
 
NAV20
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RE: 777 Fuel Consumption

Tue Apr 26, 2005 9:21 pm

Cheers Jan - no hard feelings! 'Hals und beinbruch!'

Tony
"Once you have flown, you will walk the earth with your eyes turned skywards.." - Leonardo da Vinci
 
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sebolino
Posts: 3514
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RE: 777 Fuel Consumption

Tue Apr 26, 2005 9:25 pm

The tank capacity divided by the max. distance doesn't give the fuel consumption !!!
 
widebodyphotog
Posts: 885
Joined: Wed Jun 30, 1999 9:23 am

RE: 777 Fuel Consumption

Tue Apr 26, 2005 9:34 pm

Quoting NAV20 (Reply 10):
Agree entirely that there are lots of variables, Widebodyphotog. But they would tend, as I said, to average out, since they are likely to affect all aeroplanes equally. Further, the question was:-

Sorry, but again that assumption is fundamentally flawed...The question was about fuel consumption...

Fuel tankage has nothing to do with fuel consumption, it is only an indication of how much fuel the aircraft can carry. You assume that the specific aircraft you mentioned in your post use the entirety of their fuel tankage for the given range which is terribly wrong. Fuel consumption varies with takeoff weight. Do you know what takeoff weights Boeing uses for the range figures you quote from them? Or the actual fuel loads needed to make those ranges? Assuming max fuel loads is not rough guessing, it's just plain wrong. It is impossible for the 777-200ER to load 301 passengers and maximum fuel which your analysis assumes.

I'm not sure what you mean by factors that effect aircraft equally. Even if you take into account things like weather and routing, they have little to do with the rate of fuel consumption. They have specific effects on the mission by increasing or decreasing the amount of time the aircraft stays in the air which determines total fuel burn but does not effect the rate of consumption generally. For a given flight time an aircraft with a higher rate of fuel consumption will burn more fuel during that time (duh). And when taking into account factors that increase or decrease flight time required fuel loads increase by the specific needs of that aircraft. That increase or decrease in fuel load is not the same for all aircraft for a given increase in flight time.

Quoting NAV20 (Reply 10):
I'm the only person who has offered any kind of answer so far. If you can produce a more sophisticated and accurate analysis, please put it on. Otherwise, I don't see the point of criticizing my figures while offering none at all of your own?

I believe I gave very specific and accurate figures to answer the question. The best answer to the question of fuel consumption is to give numbers on fuel consumption per hour and that's what I did including the condition, TOW, at which those rates occur.

Sorry to be so critical, but the path you took was absolutely incorrect.


-widebodyphotog
If you know what's really going on then you'll know what to do
 
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sebolino
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RE: 777 Fuel Consumption

Tue Apr 26, 2005 10:02 pm

By the way, it makes me think that the equation is a little more complicated than that, because the fuel consumption decreases with time, as the plane gets lighter when it burns the fuel.
It gives a differential equation of the type C' = KC.


It may look like this: C = C0.exp (-a.t) where a is positive.

So what can we say about the consumption by hour ? Probably only what it is when the plane is at max. weight.

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